Work handling device

ABSTRACT

A device for handling thin, waferlike elements and by which such elements can be transferred discretely from a supply stack to a rotatable carrier and from said carrier to a receiving stack. The transfer is accomplished by a mechanism that is operated in timed relation to the rotation of the carrier and by means of a vacuum that is applied for a period of time sufficient to effect the transfer. The mechanism includes an arrangement of members whereby one of the members is maintained in a path of movement that is the same as that of said element when on said carrier. During such maintenance period, the element is deposited on the carrier or removed therefrom.

United States Patent [72] Inventor [21 Appl. No. [22] Filed [45]Patented [73] Assignee [54] WORK HANDLING DEVICE 6 Claims, 10 DrawingFigs.

[52] US. Cl 214/8.5, 214/1 [51] Int. Cl B65g 59/04 [50] Field ofSearch214/1BS3,

lBS4, IB3, 1B4, 18, 147T, 8.5, 8.5C, 8.5D

Primary Examiner-Gerald M. F orlenza Assistant Examiner-George F.Abraham Attorney-Lloyd F. Seebach ABSTRACT: A device for handling thin,waferlike elements and by which such elements can be transferreddiscretely from a supply stack to a rotatable carrier and from saidcarrier to a receiving stack. The transfer is accomplished by amechanism that is operated in timed relation to the rotation of thecarrier and by means of a vacuum that is applied for a period of timesufficient to effect the transfer. The mechanism includes an arrangementof members whereby one of the members is maintained in a path ofmovement that is the same as that of said element when on said carrier.During such maintenance period, the element is deposited on the carrieror removed therefrom.

PATENIEB JAN 51971 35525 4 saw 1 OF 9 I271 VACUUM ROBERT 6'. NE/ CHINVENTO PATENTEU JAN 51971 SHEET 5 BF 9 AGE/VT PATENTEU JAN 5 l97l SHEET5 (IF 9 I N VENTOR PATENTH] JAN 5 I97! SHEEY 8 BF 9 NFW (I IIIPIIII.IIMJIIIIII WORK HANDLING DEVICE This application is a division of mycopending application Ser. No. 606,908, filed Jan. 3, 1968, now U.S.Pat. No. 3,492,762 issued Feb. 3, 1970.

The present invention relates to a lapping device and more particularlyto such a device for simultaneously lapping the planar surfaces of eachof a plurality of elements to precise thickness and a parallelismtolerances.

It is well known in the lapping art to provide apparatus that is capableof imparting a smooth surface to a planar surface or to a peripheralsurface of an element. In such apparatus the element is usually made ofmetal and the problem of damage to the elements by breakage, chippingand/or marking of another element being worked on is an ever presentpossibility. In such apparatus, the need for closely controlling thedegree of flatness of a planar surface, or the curvature of a peripheralsurface, is not as difficult to accomplish when compared to more brittlematerials, such as glass, ceramic material, etc.

In the field of glass polishing or lapping, it is customary to mountglass discs or lenses on a carrier member by means of pitch or othersuitable materials. The carrier is usually rotated, or rotated andoscillated, with respect to the polishing member. Due to thecharacteristics of glass, particularly its brittleness, a chip from oneelement that is carried under the polishing member can damage the otherelements on the carrier. As a result, the entire group of elements canbe scratched or made unusable merely due to the cracking or chipping ofone of the elements.

In the electronics field a very thin piece of a crystal, such asgeranium, silicone and/or a similar material, is used as the basicelement for a transistor. The small piece of crystal is obtained fromartificially grown crystals that are usually encapsulated in plastic andthen cut into thin wafers. The planar surfaces of the wafers are thenlapped or polished until a required thickness, and parallelism of thesurfaces as well as very smooth surfaces are attained. The wafers arethen cut into small rectangular pieces that are ultimately made intotransistors. Due to the cost of the original crystal, it is desirable toobtain as many wafers as possible from each crystal so as to maintain aminimum cost for each transistor element.

Lapping devices for thin crystal wafers, which are only several milsthick, have been devised which follow the general principles for lappingor polishing glass. However, the same shortcomings are prevalent in suchwafer lapping devices as in the polishing apparatus used for glass. Dueto the high cost of the crystal material, it is desirable to eliminatethe possibility of damaging all or even a number of the wafers beinglapped when one becomes broken during the lapping process.

A primary object of the invention is to provide an improved device forsimultaneously lapping a planar surface of each of a plurality ofelements.

Another object of the invention is to provide an improved lapping devicewherein elements of different thicknesses can be lapped to attainelements of uniform thickness, the amount of material removed from thesurface of each such element being automatically and individuallycontrolled.

A further object of the invention is to provide an improved lappingdevice which is capable of continuous operation, removes the materialfrom each element at a fast rate, and requires a minimum of manualhandling of the elements during the lapping operation.

Still another object of the invention is to provide an improved lappingdevice in which each element being lapped is rotated in a directionopposite to that of the lapping wheel and in which such rotation of theelement is commenced prior to its full engagement with the wheel so asto substantially eliminate any initial engagement of a high area on theelement with the wheel and to provide random surface contact with thewheel. v

And yet another object of the invention is to provide'an improvedlapping device in which each element is automatically positioned on acarrier rotated during its movement into and out of engagement with alapping wheel, and automatically removed from the carrier after thelapping operation has been completed.

Other objects and advantages of the invention will be apparent to thoseskilled in the art by the description of a preferred embodiment of theinvention which follows:

The above objects of the inventionare attained by a carrier thatcontinuously moves a plurality of elements in a path, preferably anarcuate path, which extends across a portion of a rotating lappingsurfaceor wheel. Each of the elements is supported upon a rotatablemember having means for controlling the amount of material to be removedfrom its respective element by the lapping surface. Only thosesupporting members immediately ahead of, aligned with and immediatelybeyond the lapping surface are rotated so as to eliminate anypossibility of damaging the element upon being moved into engagementwith the lapping surface. The elements are arranged in a magazine aheadof the lapping wheel and are removed individually therefrom forpositioning each element on a support member. On the other side of thelapping wheel, a similar device is arranged for removing each elementfrom its respective supporting member and positioning it in a receivingmagazine. Movement of each element onto its respective support member,retention thereon and removal therefrom is accomplished by controlledvacuum means so as to eliminate any mechanical handling of the elementas well as any possibility of breakage or damage. Since the lappingdevice described in more detail hereinafter is fully automatic and'hasmeans for controlling the amount of material to be removed, the lappingspeed can be greatly increased, thereby increasing the number ofelements that can be lapped in a fixed period of time.

Reference is now made to the accompanying drawings wherein like numbersdesignate like parts and wherein:

FIG. 1 is a plan view of a preferred form of the invention showing therelation of the load and unload stations to the lapping wheel;

FIG. 2 is a front elevation of the lapping device;

FIG. 3 is a vertical section through the carrier member and a supportmember thereon taken substantially along line 3-3 in FIG. 1;

FIG. 4 is a partial sectional view through the central support for thecarrier member;

FIG. 5 is a plan view taken along substantially the line 5-5 in FIG. 3and showing particularly the drive means for the support members;

FIG. 6 is a plan view showing the relationship of the loading mechanismto the supply magazine for the elements and the support member on whichthe elements are positioned;

FIG. 7 is a side elevational view taken substantially along the line 7-7in FIG. 6 and showing the vacuum controlled means;

FIG. 8 is a side elevational view showing the relationship of the loadmechanism to a supporting member on the carrier when an element is beingpositioned thereon;

FIG. 9 is a schematic arrangement of the vacuum and lubricating systemused in conjunction with the lapping device; and

FIG. 10 is a schematic arrangement of the electrical components used inconjunction with the lapping device.

With particular reference to FIGS. 1, 2 and 4 a support means 10comprises a bedplate 11 which is mounted on a suitable framework notshown so that the bedplate is positioned at a workable height for theoperator. A lapping member 12 is rotatably mounted in a bracket 13 thatis fixed to a support bracket 14 which, in turn, is mounted on thebedplate 11. I

The lapping member 12 comprises a cast disc I5 having a lapping wheel 16secured thereto in any well known manner. The lapping member 12 overliesa carrier 20 on which a plu rality of supporting members 21 arerotatably mounted. The carrier 20 is rotated by a separate drive motor22 and moves the supporting elements in an arcuate path across a portionof the lapping wheel 16, as seen in FIGS. 1 and 5. Loading orpositioning means 23 is arranged adjacent the carrier and serves toremove the uppermost element 24 in a magazine 25 and position it on oneof the supporting members 21 as the latter is moved past the loadingmeans. A similar device 26 referred to as an unloading or removing meansis arranged on the other side of the lapping member 12 and adjacent thecarrier 20 for removing each of the elements 24, after they have beenlapped, from their respective supporting member 21 and positioning theelement in a receiving tank magazine 27.

The lapping member 12, see FIG. 4, is keyed to one end of a shaft 30that is journaled in bearings 31 arranged within a sleeve 32 that isaxially movable in bracket 13 and held against rotation by a suitablekey connection not shown. The upper end 33 of sleeve 32 has a threadedportion 34 that threadably engages a rotatable collar 29. A worm wheel35 is fixed to collar 29 and engages a worm 36 on a shaft 37 that isdriven by a motor 38 by means of a pair of gears 47. The shaft 30 has apulley 39 keyed thereto at the end opposite the lapping member 12.Pulley 39 is connected by a belt 40 to a pulley 41 on shaft 42 of amotor 43. Motor 43 is fixed to a plate 44 that is pivotally mounted at45 to support bracket 14. By means of an adjusting screw 46 thatthreadably engages plate 44 and bears against support bracket 14,- thetension in belt 40 can be varied.

The lower portion 53 of sleeve 32 threadably engages a collar 48 whichby means of a plurality of springs 49, as shown in FIG. 2 and 4, toprovide a continuous thrust on collar 29 so as to keep the latter inengagement with bracket 13, the springs 49 being retained in part bypins 54. Bracket 13 carries a segment lock 50 that is releasable by knob51 and serves to maintain sleeve 32 in its adjusted position. However,upon release of lock 50, motor 38 can be energized to drive worm 36 andworm wheel 35 thereby moving sleeve 32 and by means of the threadedportions 34, 53 the lapping member 12 is moved in an axial direction forpositioning the lapping surface 16 relative to the elements 24 oncarrier 20. By this means the finished thickness of the element 24 canbe varied and controlled within very exact limits.

The carrier 20, see FIGS. 13, comprises a cast disc 55 that is mountedon a collar 56 which, in turn, is part of a sleeve 57 journaled inbearings 58 contained in the cylindrical housing 59 that depends fromthe upper surface of bedplate 11, as shown in FIG. 3. Sleeve 57 carriesa pulley 60 that is driven by belt 61 from a pulley 62 on the shaft ofmotor 22.

As seen in FIG. 1, carrier 20 has a plurality of element supportingmembers 21 mounted adjacent the peripheral edge thereof. With referenceto FIG. 3, the structure of one of the supporting members 21 will bedescribed, all of said members being identical in structure. A sleeve 65is fixed to carrier 20 and supports a pair of spaced bearings 66 inwhich a rotatable sleeve 67 is mounted. At one end, sleeve 67 carries apulley 68 and within sleeve 67 another sleeve 52 is slidably mounted,the latter having a recessed cap 69 fixed to one end thereof on which anelement 24 is retained in a manner to be described more fullyhereinafter. Within sleeve 52 a follower 70 is slidably mounted, thefollower 70 including a ball 71 which engages the top surface 72 ofbedplate 11 until member 21 is moved into engagement with a plate cam 73having a ramp 74 at each end that joins the top surface 72 of bedplate11 with the top surface of the plate cam 73. Follower 70 is urged towardplate cam 73 by a spring 75 whose compression can be adjusted by a screw76 within sleeve 52. The amount of vertical movement of element 24toward lapping wheel 16 is determined by a collar 77 which threadablyengages the other end of sleeve 52. A spring 78 arranged between sleeve67 and collar 77 normally urges cap 69 away from lapping wheel 16.Spring 78 works in conjunction with spring 75 to determine the forcewith which the element 24 is urged against the lapping wheel 16, untilcollar 77 abuts the end of sleeve 67 at which time no further cuttingaction can occur.

With reference to FIG. 5 the drive means for rotating the supportingmembers 21 comprises a motor 80 which drives a pulley 81 connected by abelt 82 to a pulley 83. A plurality of pulleys 84 are arranged aroundthe periphery of carrier 20 in a pattern, as seen in FIG. 5, and areconnected by a belt 85 to the one pulley 84 that is on the same shaft aspulley 83. The pulleys 84 are arranged in the same plane as the pulley68 on each of the supporting members 21. The configuration of pulleys 84and pulleys 68 is such that belt 85 engages at least two of the pulleys68 on either side of the lapping member 12 and those on the supportingmembers 21 immediately under the lapping member 12. An adjustable belttightener 86 is arranged on each side of the lapping member 12, as shownin FIG. 5. With this arrangement, the drive means for supporting members21 is coupled only to those of the supporting members moved intopositions immediately ahead of, aligned with and immediately beyond thelapping member 12. The supporting members 21 so engaged by belt 85 aretherefore rotated so as to provide random surface marks on the element24 as it is moved through a path in which it is in engagement with thelapping wheel or surface 16.

The means for positioning an element 24 on each of the supportingmembers21 and for removing the element 24 from each of said supporting members21 is shown diagrammatically in FIG. 1 and in detail in FIGS. 6-8. Thesedevices 23 and 26 are substantially the same in construction and areoperated in timed relationship to movement of the supporting memberrelative thereto to perform their respective load and unload function.The description relative to stations 23 and 26 is therefore describedonly with respect to the load station 23.

With reference to FIGS. 6-8, a support or bracket 90 is mounted onbedplate 11. and carries a plate 91 that is pivotally mounted thereon bymeans of a stud 92. At the left-hand end of plate 91 as seen in FIG. 8,an air cylinder 93 is mounted and has its piston rod 94 connected to aplate 95 that is slidably mounted on plate 91. At the right-hand'end ofplate 95, a pair of spaced and freely rotatable rollers 96 are mounted,see FIG. 6. Plate 95 is provided with an elongated slot 97 that isengaged by a pin 98 fixed to plate 91 and through which a cam follower102 extends, the slot, pin and cam follower providing mean for guidingplate 95 as it is moved relative to plate 91. A plate 99 is pivotallymounted on plate 95 by means of a stud 100, the plate 99 being providedwith a cam slot 101 that is engaged by the follower 102 carried by plate91. At the righthand end of plate 99, a bracket 103 is secured theretoand carries connectors 104 and 105 that are coupled to a vacuum sourceand an air source, respectively, for delivery of the same to a pickupmember 106 which depends from bracket 103. Magazine 29 is mounted onbedplate 11 and is of a well known structure in which the uppermostelement 24 is maintained at a predetermined level.

Let it be assumed that pickup member 106 is positioned over a supportingmember 21 at the start of a cycle, as shown in FIG. 6. A switch LS3 willthen have been actuated by a member 21 as it moved in a clockwisedirection (FIG. 6) so that, as described hereinafter, air is beingapplied to cylinder 93 for urging plate 95 in a direction to holdrollers 96 against member 21. As the supporting member 21 is moved bycarrier 20, plates 91 and 95 pivot counterclockwise about stud 92 untilplate 91 strikes plunger 110 and moves the latter sufficiently toactuate a switch LS4. The air supply to cylinder 93 is then reversed andplate 95 is drawn toward the cylinder. At the same time, the plunger 110urges plates 91 and 95 in a clockwise direction about stud 92 untilplate 91 abuts pin 114 and further'pivotal movement of plates 91 and 95is arrested due to pins 98 and 114. However, plate 95 continues to movetoward plunger 93. Since plate 99 is pivotally mounted on plate 95 andinterconnected by cam slot 101 and follower 102, the movement of plate95 toward plunger 93 causes plate 95 and bracket .103 to pivot as a unitin a clockwise direction about stud 100 until pickup member 106 is overmagazine 25. At this point, switch LS3 is again actuated and thedirection of movement of plunger 93 is again reversed with the vacuumsource then being connected to the pickup member 106 to pick up andremove an element 24 from the magazine 25. As

the plunger 93 moves plate 95 toward carrier 20, the plate 95 is alsopivoted about stud 100 due to cam slot 101 and follower-102. Whenrollers 96 engage the member 21 on which the element 24 is to bepositioned, the pickup member 106 will then be over the same member 21.At this time the vacuum will be cut off from the member 106 and a blastof air will be applied to element 24 to effect transfer thereof to themember 21 on which it is also held by vacuum. This transfer takes placeduring the interval that the entire unit is being moved as describedabove, the complete cycle then being repeated. A more detailedexplanation of the controls for the vacuum system follows with respectof FlGS. 9 and 10.

The cycle of operation described above occurs in an interval of timesuch that discrete elements 24 can be removed from the magazine 25 andpositioned on each of members 21 as the latter are moved successivelypast the load station by the carrier 20. This same cycle of operation isfollowed with respect to unloading means 26 and receiving tank magazine27. For removing an element 24, the pickup member 106 is moved with themember 21 for pickup, then to the magazine 27 for depositing it thereinand then returns to its initial starting position over the next member21, the difference being that an element 24 is deposited in the magazine27, rather than removed therefrom. ln order to limit the movement of theplates 91, 95 an 99 and for controlling the application of a vacuumsource to the pickup member 106 via connection 104 and 105, aspring-biased plunger 110 is mounted on the support 90 as shown in FIG.7. A threaded extension 111 has an adjustable collar 112 for engaging aswitch LS4 associated with the control circuitry for the vacuum source.From FIG. 6 it will be readily evident that plunger '110 is operatedonly after pickup member 106 is positioned over one of the supportingmembers 21 and the plates 91, 95 and 99 are moved as a unit by carrier21 through the medium of rollers 96. The angular movement of the platesis therefore controlled by plunger 110 and switch LS4, plunger 110 alsoserving to return plate 91 to its initial position against the stop pin114 on support 90, as previously described.

The means for controlling the application of a vacuum source to thesupport members 21 is shown in FIG. 3. The carrier is provided with aplate 120 that is secured to the carrier by means ofa screws 121. A lead122 for vacuum and a lead 123 for air extend through a sleeve 119 withinsleeve 57 and terminate in a stationary cap 124. The cap 124 isseparated from the plate 120 by means of rings 125 and 126 which aresecured respectively to plate 120 and cap 124. The rings 125, 126 aremade of a suitable antifriction material, such as Teflon, and areprovided with arcuate slots 127 (vacuum), 128 (air) in ring 126 and aplurality of holes 129 which are angularly'spaced in ring 125 inaccordance with the angular spacing of support elements 21. The slots127, 128 are connected to the leads 122, 123, respectively, by radialholes 131, 132 and axial holes 131', 132. Each of the holes 129 isconnected by a hole 130 in plate 120 to a radial hole 133 which extendsto the periphery of plate 120 for receiving a connection 134 on one endofa tube 135. The other end of tube 135 is joined to a connector 136which is threaded into a hole 137 in the supporting member 21. This hole137 is connected by a plurality of holes in various parts of supportingmember 21 to provide a passageway 138 to the stem of cap 69 on which anelement 24 is positioned during movement between the load station 23 andthe unload station 26.

With reference to FIG. 1 it will be noted that the slots 127 and 128 incap 124 bear a particular relationship to the loadbottom of the element,via holes 132, 131, slot 128, holes 129, 130, 133, tube and passageway138 to move it toward the pickup member 106' in the unloading station26. The continued application of air to the supporting member 21 removesany accumulated coolant before it reaches the loading means to acceptanother element 24.

in order to describe, the operation of the lapping device morecompletely, reference will now be made to the diagrammatic disclosuresof the vacuum and electrical components shown in FIGS. 9 and 10.Assuming that the supply magazine 25 has been filled with a plurality ofelements 24. the loading means 23 and the unloading means 26 are each ina position relative to a supporting member 21, and the main switch SW1has been closed to provide a source of potential for the variousoperating and control components. Switch SW2 is then closed .whichenergizes lamp L1 to indicate its closed position and also the solenoidvalve 5V1 for supplying air to the lead or line 123. With closure ofswitch SW3, lamp L2 is energized as well as relay R1 which closes itscontact R1A in the circuit of the motor 139 for the vacuum pump 140.Vacuum is then supplied to lead 122 under control of vacuum valves 1 50and 151, to the load means 23 under control of solenoid valve SV10 andto the unload means 26 under control of solenoid valve SV13. Switch SW4is then closed, thereby energizing lamp L3 and solenoid valve SV2 whichcontrols the application of the coolant to the lapping member 12. Theclosure'of switch SW5 energizes lamp L4 and relay R2 which, in turn,causes closure of its contacts RZA and R213 to energize motor 43 fordriving the lapping member 12. With closure of relay contact RZC, switchSW6 can be closed to energize lamp L5 and relay R3,

5 thereby closing its contacts R3A, R38 and R3C. The closure of contactR3A and R3B cause motor 22 to be energized, thereby driving the carrier20 with the supporting members 21 thereon. With contact R3C closed, theswitch SW8 can be closed, thereby energizing lamp L6 and relay R4 andclosing its contacts R4A and R48 to energize motor 80 for driving thesupport members 21 that are under and in proximity to lapping member 12by means of pulleys 84 and belt 85.

At this point the lapping device is completely operative with thevarious motors energized and the vacuum source and air 7 sourceoperating and connected to various solenoid-operated control valves. Thelapping coolant is connected by lines 141 and 142 to nozzles 148, 149located adjacent the lapping member 12 to provide the necessary cuttingaction between the surface 16 and the surfaces of the elements 24 thatare being held against surface 16. The coolant is also connected by line143 via valves SVS and SV6 to a pair of moisture trap tanks 144 and 145.A limit switch LS1 is associated with tank 145 and a limit switch LS2,is associated with tank 144. By means of these switches, as describedhereinafter, only one tank at a time is operative to receive anymoisture that may be introduced into the vacuum system. Assuming thattank 145 is filled, the switch LS1 which is controlled by a float 146has its contacts LSlA and LS1B closed thereby energizing relay R5 whichwill be held in with closure of its contact RSA and closed switch LS2 sothat solenoid valve SVS will be energized to a shutoff position toprevent any more moisture from entering tank 145. Relay R5 will alsoclose its contacts R513 and RSC to energize the 4-way solenoid valvesSV3 and SV4 to control entry of air into the proper tank. Tank 144becomes operative as tank 145 is being emptied via relay contact RSDwhich is opened to deenergize solenoid valve 5V8 to close the drain endof the tank, and with float 147 in an empty position the contacts LSZAand LS2B of switch LS2 are closed, so that solenoid valve SV6 isenergized and opened to permit entry of any moisture into tank 144. Whentank 144 is filled, the contacts of switch LS2 are opened, relay R5 isdeenergized and functions of the valves are reversed, that is SVS and5V8 are opened and SV6 and SV7 are closed. With this arrangement thereis no shutdown time required for draining moisture from the vacuumsystem.

With the actuation of the switches in proper sequence as describedabove, the carrier 20 is moving the supporting memmeans of thedistributor valve comprising plates 125 and 126 associated with sleeve57. The vacuum is applied to each supporting member from the time itreceives an element 24 at supply station 23 until the same element 24has been moved out from under the lapping wheel 16. As the same element24 approaches the unloading station 26, air is then applied to theunderside of the element 24 to aid in its being withdrawn from thesupporting member 21 by the pickup member 106 associated with theunloading mechanism.

A switch LS3, see FIG. 1, is located adjacent the load station 23 and isactuated in proper. timed sequence by the peripheral edge of eachsupporting member 21 as it passes thereby. A switch LS4 is actuated bycollar 112 and a switch LS5 is actuated by a similar collar by themechanism in the unload station 26.

With reference to FIG. 10, the momentary closing of switch LS3 by asupporting member 21 on carrier 20 causes relay R6 to he energized whichcloses its contract R6A to energize a relay R7. Simultaneously, contactR68 is closed thereby energizing a relay R8. Relays R7 and R8 are heldin by their respective contacts R7A and RSA in conjunction with switchesLS4 and LS5. The contact R78 is also closed with the energization ofrelay R7, thereby energizing the solenoid valves 5V9 and SV and R7C isopened to deenergize and open solenoid valve SVll. Solenoid valve SV9 isclosed when energized to permit air to be supplied to cylinder 93 viaSVll for urging the load mechanism toward the supporting member 21 asdescribed above. Also, solenoid valve SV10 is closed to disconnect thevacuum source to pickup head 106 for releasing the element 24 with airsupplied via SV 11. At the same time, contact R88 is closed therebyenergizing solenoid valve SV12 which shuts off the air supplied tocylinder 93 for actuating the unload mechanism 26 and to pickup head106'. At the same time, contact R8C is opened thereby deenergizingsolenoid valves SV13 and Sv14 and so that the vacuum is applied topickup head 106 whereby an element 24 is picked up. The closing ofsolenoid valve SV14 causes the air supply to actuate cylinder 93' in adirection to move pickup head 106 toward magazine 27. When switch LS4 isactuated by collar 112 the action of the loading mechanism is caused toreverse as already described. With LS4 opened, relay R7 is deenergizedthereby permitting solenoid valves 8V9, SV10 and SV11 to return to theirinitial positions, so that air is now supplied to cylinder 93 for movingit in a reverse direction and the vacuum is applied to pickup member 106to withdraw an element from magazine 25. in a similar manner, the switchLS5 associated with the unload station is opened to deenergize relay R8to cause solenoid valves Svl2, Sv13 and SV14 to return to their initialcondition when the pickup head 106 has been pivoted in acounterclockwise direction (FIG. 1), to connect the vacuum sourcethereto and which is disconnected J from the pickup member 106 forreleasing the element 24 thereon into magazine 27 with the nextactuation of switch LS3. Air is then applied to cylinder 93' to move themechanism toward carrier to retrieve the element 24 on the nextsupporting element 21. The complete cycle is repeated with the actuationof switch LS3 by the next supporting element 21.

By means of a transformer T1 and a rectifier SR1 an alarm device 117 isenergized when the supply of elements 24 are at a predetermined level inmagazine 25. This alarm is energized by a microswitch LS6 associatedwith a control member, not shown, in the magazine 25.

From the above description it will be evident that the unload and loaddevices 26 and 23 work in unison and that the vacuum and air are byswitches l LS3 and LS4. As each element 24 is moved by the carrier 20toward the lapping wheel 16, the ball 71 engages the ramp 74 'to movethe element toward the wheel to remove an amount of material from thesurface engaging the wheel so that each of the elements of is of by thebelt arrangement shownin F 1G 5 so that each element 24 is brought up toa predetermined speed before actually en gaging the cutting surface ofwheel 16. thereby producing a surface having random cutting marks.

As described above, a coolant is used as a lapping lubricant and sinceit is directed against elements 24 and wheel 16, provisions must be madeto remove the coolant that is drawn into the vacuum system. It is inconnection with removal of this coolant from the vacuum system thattanks 144 and 145 are used.

The invention has been described in detail with particular reference topreferred embodiments thereof, but it will be understood that variationsand modifications can be effected within the spirit and scope of theinvention.

lclaim:

1. A device for positioning each successive element presented by a stackof said elements on a respective one of each of a plurality ofsupporting members arranged on a movable carrier, said stack-of elementsbeing arranged adjacent said carrier, the combination comprising:

a first support member;

a second support member pivotally mounted on said first sup ort member;

reversible drive means arranged on said second support member; a vacuumsource; first means pivotally and slidably mounted on said secondsupport member and coupled to said drive means for cyclic movementbetween a first position in which it is disengaged from one of saidsupporting members, a second position in which it engages and is held inengagement with one of said supporting members, and a third positioninto which it is moved with said second support member by said carrier;

second means connectable to said vacuum source and pivotally mounted onsaid first means and movable therewith and relative thereto between afirst position relative to said stack for picking up one of saidelements and a second position relative to one of said supportingmembers for positioning said one element on said supporting member;

means interconnecting said first and second means and said secondsupport means so that movement of said drive means in one directionmoves said first and second means from said first portions to saidsecond positions and maintains said first and second means in saidsecond positions relative to said one supporting member during apredetermined movement of said carrier and in the other directionreturns said first and second means to said first position; and

means responsive'to movement of each successive supporting member into apredetermined position relative to said stack for connecting said vacuumsource to said second means and for initiating movement of said drivemeans in said one direction, and to movement of said second supportmember into said third position for disconnecting said vacuum sourcefrom said second means to release said one element and for reversing thedirection of movement of said drive means.

2. A device in accordance with claim 1 wherein said interconnectingmeans comprises a pair of spaced pins fixed to said secured supportmember, one of said pins engaging a longitudinal slot in said firstmeans and the other pins extending through said slot and engaging a camslot in said second means, said pins and slots being arranged betweenthe pivotal axes for said second support member, first means and secondmeans, on the one hand, and said carrier, on the other hand.

3. A device in accordance with claim 1 wherein said second meanscomprises a plate pivotally mounted on said first means and movabletherewith and relative thereto, a third support tier fixed to saidplate, and an element engaging means secur' d to said third supportmember and connectable to said vacuum source.

thereof for engaging each of said supporting members when said plate isin said second position and being held in such engaging relationship formaintaining said second means in said second position until said oneelement is positioned on said supporting means.

1. A device for positioning each successive element presented by a stackof said elements on a respective one of each of a plurality ofsupporting members arranged on a movable carrier, said stack of elementsbeing arranged adjacent said carrier, the combination comprising: afirst support member; a second support member pivotally mounted on saidfirst support member; reversible drive means arranged on said secondsupport member; a vacuum source; first means pivotally and slidablymounted on said second support member and coupled to said drive meansfor cyclic movement between a first position in which it is disengagedfrom one of said supporting members, a second position in which itengages and is held in engagement with one of said supporting members,and a third position into which it is moved with said second supportmember by said carrier; second means connectable to said vacuum sourceand pivotally mounted on said first means and movable therewith andrelative thereto between a first position relative to said stack forpicking up one of said elements and a second position relative to one ofsaid supporting members for positioning said one element on saidsupporting member; means interconnecting said first and second means andsaid second support means so that movement of said drive means in onedirection moves said first and second means from said first portions tosaid second positions and maintains said first and second means in saidsecond positions relative to said one supporting member during apredetermined movement of said carrier and in the other directionreturns said first and second means to said first position; and meansresponsive to movement of each successive supporting member into apredetermined position relative to said stack for connecting said vacuumsource to said second means and for initiating movement of said drivemeans in said one direction, and to movement of said second supportmember into said third position for disconnecting said vacuum sourcefrom said second means to release said one element and for reversing thedirection of movement of said drive means.
 2. A device in accordancewith claim 1 wherein said interconnecting means comprises a pair ofspaced pins fixed to said secured support member, one of said pinsengaging a longitudinal slot in said first means and the other pinsextending through said slot and engaging a cam slot in said secondmeans, said pins and slots being arranged between the pivotal axes forsaid second support member, first means and second means, on the onehand, and said carrier, on the other hand.
 3. A device in accordancewith claim 1 wherein said second means comprises a plate pivotallymounted on said first means and movable therewith and relative thereto,a third support member fixed to said plate, and an element engagingmeans secured to said third support member and connectable to saidvacuum source.
 4. A device in accordance with claim 1 wherein saidreversible drive means comprises a fluid operated member.
 5. A device inaccordance with claim 1 wherein said reversible drive means comprises apneumatically operated member.
 6. A device in accordance with claim 1wherein said first means comprises a pivotally mounted plate having apair of spaced and freely rotatable rollers mounted on one end thereoffor engaging each of said supporting members when said plate is in saidsecond position and being held in such engaging relationship formaintaining said second means in said second position until said oneelement is positioned on said supporting means.